In the conventional roller screen unit, the screen is drawn and rolled up in the winding means with the clutch mechanism usually arranged in an upper position of the window frame or in the ceiling. In order to perform an automatic winding operation a sleeve for rolling up the screen is loaded with a spiral spring which at its one end is fixed and connected at its opposite end to a pillow rotatable in accordance with the rolling operation of the roller so that a torsion power is accumulated in the spiral spring. The drawing operation of the screen or the discontinuation thereof may be performed in accordance with engagement or disengagement operation of the clutch mechanism.
According to the conventional clutch mechanism an engaging pawl when incorporated into the winding means is moved in the direction of its gravity or the vertical direction and also the power balls or rollers used in the clutch mechanism are moved only in the vertical direction as the screen is generally drawn or extended perpendicularly. Hence, when it is desired to draw or roll off the screen in the lateral direction the clutch mechanism is left in the engaged or disengaged position rendering the use of the screen unit impossible.
The latest diversity of life, however, requires the use of the screen unit in various directions and any convenient positions upon options of users. The clutch mechanisms heretofore proposed, however, could not fulfill such requirements.
Furthermore, in the conventional screen unit a rotary sleeve is turnably mounted on the fixed shaft which is interconnected with a terminal of the spiral spring and the rotary sleeve is connected to the roller sleeve. The bearing section of the fixed shaft against the rotary sleeve is relatively small for which reason undesired relaxation is caused to disturb the smooth turning operation of the roller sleeve.